As an image forming apparatus including a function for restricting usage of various types of functions of copying, PC printing, scanning, facsimile transmission and receiving, etc, there has been proposed a known image forming apparatus that authenticates a user and restricts usage of a part of functions or the number of times of usage of the functions in accordance with usage restriction information of each user.
The known image forming apparatus also includes a function for carrying out an image quality adjusting process (so-called “calibration,” etc.), which measures deviation in respective colors of image formed positions and deviation in density of the respective formed colors and corrects the deviations. The image quality adjusting process is triggered by a printing request from a user and is executed if predetermined conditions are satisfied, for example, if a number of printed sheets after the last image quality adjusting process exceeds the predetermined number.